Question

The energy difference between the first two levels of hydrogen atom is 10.2 eV. For another element of atomic number 10 and mass number 20, this will be

• A. 2040 eV
• B. 0.201 eV
• C. 510 eV
• D. 1020 eV

Answer 1

The correct option is D

1020 eV

For H atom

$E_2-e_1=10.2eV$

$E=\frac{-13.6}{n^2}{Z}^2$

For Z = 10,

$E_1=\frac{-13.6\times {10}^2}{1^2}=-1360eV$

$E_2=\frac{-13.6\times {10}^2}{2^2}=-3.4\times 100=-30eV$

$\therefore E_2-E_1=-340-(-1360)=1020eV$